ip[6]tables: only call target's parse function when option char is in range

Same as previous commit. Doing this actually allows to remove code
that is no longer needed.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
diff --git a/ip6tables.c b/ip6tables.c
index 4ca4bfe..d4c2339 100644
--- a/ip6tables.c
+++ b/ip6tables.c
@@ -1706,6 +1706,8 @@
 
 		default:
 			if (target == NULL || target->parse == NULL ||
+			    c < target->option_offset ||
+			    c >= target->option_offset + XT_OPTION_OFFSET_SCALE ||
 			    !target->parse(c - target->option_offset,
 					       argv, invert,
 					       &target->tflags,